Dieter Spaar spaar at
Tue Mar 16 11:07:43 UTC 2010

Hello Sebastien,

On Tue, 16 Mar 2010 10:04:07 +0100, "=?UTF-8?Q?S=C3=A9bastien_Lorquet?=" <squalyl at> wrote:
> I know that smart card EEPROMS are rated for 100k writes, but I would not
> rely on that. In fact, this depends on how often is the EF.Kc file written,
> which was my original question. Every 30 seconds or every day? Every day is
> of course OK.

It is only written if an AUTHENTICATION REQUEST from the network is
performed. This usually happens when the phone is turned on and
does a location update. The network can also perform an AUTHENTICATION
REQUEST when doing a call or similar things, however usually this is
not done every time and the previous Kc stored on the SIM is reused
as Sylvain explained it. For OpenBSC and OpenBTS the default is that
there is no AUTHENTICATION REQUEST at all, so no Kc is written (I am
not 100% sure if this is true for OpenBTS, but I guess so).

> Additionally, how often are these other files written (LOCI, BCCH) ?

They are written when a location update is done or the cell changes.
However it depends on the phone if the data is really written to the
SIM every time, sometimes the phone caches those data and writes them
to the SIM only when the phone is turned off. For OpenBSC and OpenBTS
writing should not happen that often because there is usually only one
cell with fixed parameters. And I guess you will probably not actually
write to the EEPROM if the same data is already stored (or a least 
the Card OS should do it this way).

> SmartCardFocus has a ID0 cutting service, that can turn any card into a SIM
> sized module:
> This is the best option I know so far.

Thanks, I did not know that. It would be interesting to know what tool
they use and if it is available for a reasonable price.

> However for devel purposes, as layer 2-3 will be developed on a PC, most
> people will need/use a PCSC reader and a normal sized card. Any javacard
> will do, even dual interface cards such as JCOP31 or Cosmo or older
> Cyberflex. my applet will have no specific requirement on javacard support,
> JC 2.1.x or 2.2.x will do.

Yes, sure.

Best regards,
Dieter Spaar, Germany                           spaar at

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